Noncollinear optical parametric amplifiers (NOPAs) generating sub-20 femtosecond pulses in visible were demonstrated in the late 1990s. Despite significant improvements in spectral bandwidth and stability, the NOPA can be a tedious optical tool because of its strict alignment requirements and its sensitivity to perturbations. The geometry of a traditional NOPA is similar to a Michelson interferometer, in which the beams travel separate paths before recombining. Researchers have shown that a common-path geometry—wherein the two beams never encounter individual reflective optics—can significantly reduce fluctuations in a variety of optical devices; for example, a common-path interferometer, which is largely immune to vibrational perturbations, has been employed to obtain high accuracy phase measurements with a liquid crystal spatial light modulator.
Additionally, researchers have made simple modifications to optical microscopes based on common-path interferometric stabilization, resulting in enhanced optical resolution in aperture limited systems. In nonlinear optics, a common-path approach significantly increases second-harmonic generation signals, and most two-dimensional electronic spectrometers rely on the passive stabilization provided by a common-path geometry. While a NOPA is distinct from an interferometer because a NOPA utilizes a pump that is polarized perpendicular to the seed, the phases of the pump, signal, and idler are important, and the stringent spatial overlap requirements makes the comparison between the devices both natural and productive. The NOPA remains an imposing optical tool because of its strict alignment requirements and its sensitivity to environmental perturbations such as air currents and mechanical vibrations. Prior NOPA designs are based on an adjustable pathlength Michelson interferometer (M-NOPA).
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the following drawings and the detailed description.